Friday, Dec. 17, 2004
Blowing A Gasket
By Jeffrey Kluger; Missy Adams
Michael Robinson, 35, is young enough to remember his glory days playing college basketball, which was one reason he was so surprised when just walking to his car started to wear him out. Robinson's weight certainly didn't help: 345 lbs. is a load to carry, even on a 6-ft. 9-in. frame. His family history worked against him too. Both his parents have high blood pressure, and his father and brother are diabetic. And he didn't do himself any favors by allowing seven years to elapse since his last checkup. When his persistent fatigue finally drove him to a doctor, he learned the wages of so much neglect. His blood pressure was topping out at a monitor-popping 166/120, and he was in the early stages of heart failure.
A year later, the Ashburn, Va., man exercises regularly, takes hypertension medication, and has dropped his fast-food burger habit in favor of low-fat grilled chicken. He has a lower-stress job with the county department of family services and is the father of a new baby boy. "I'd like to be around for him," he says. His new blood pressure should help. It's 120/80.
Robinson's turnaround was impressive, but according to the experts, such stories are increasingly rare. At least 65 million Americans--a third of all adults over 18--are thought to suffer from hypertension (the technical term for persistent
high blood pressure), up from 50 million just 10 years ago. Worse, doctors last year defined a new category of risk, prehypertension, in a borderline pressure range that is now considered a bright red flag of trouble to come. Moreover, when people do address their blood-pressure issues, they don't always do it very well. Only about a third of all patients in treatment for high blood pressure have their numbers under control. Over the course of our lives, perhaps 90% us will develop a blood-pressure problem, and at least half of us will die from either heart disease or stroke--hypertension's frequent endgames.
Alarmingly, it's not just middle-agers and seniors who are turning up with the problem. So are kids. Dr. Keith Ferdinand treats patients in a community health clinic in one of the poorest neighborhoods in New Orleans and has lately been shocked to see more and more young patients coming in with elevated pressure. Four years ago, he treated his first 18-year-old heart-attack victim. "We're seeing not only a growing number of cases of hypertension in young people," he says. "We're also seeing a growing number of complications from it."
The blood-pressure problem was never supposed to get this far. Not all that long ago, the battle against hypertension was touted as one of the U.S.'s great public-health success stories. Almost absurdly easy to detect--a few painless seconds with a pressure cuff does it--hypertension is comparatively simple to treat with weight loss, lifestyle changes and a little medication. In the 1970s, doctors began tackling the condition aggressively, and as the percentage of people being treated crept up, the incidence of hypertension-related conditions fell. Strokes alone declined more than 50% from 1972 to 1994. Clearly, the country was closing in on a big medical win--with medications like beta blockers and angiotensin-converting enzyme (ACE) inhibitors making big contributions to that success. But the ball has been dropped, and the reasons, in retrospect, are clear.
In the cause-and-effect universe of epidemiology, societies get the blood pressure they deserve, and we Americans have earned ourselves some huge problems. We are heavier than we have ever been, with 65% either overweight or obeseincluding 15% of kids. We're lazy too. Only 24% of us exercise vigorously at least three times a week. We smoke too much (22% of adults still light up), drink too much, and with our fetish for fast and processed foods, we're practically pickling ourselves with salt.
Worse, demographics ensure that the hypertensive population is only going to grow. As the bow wave of the baby-boom generation prepares to hit 60, more than 77 million of us will begin entering our golden--and most pressure-prone--years. Following the boomers will be their kids and grandkids, with up to 3% of the juvenile population thought to be hypertensive. "More than 25% of children with high blood pressure may already have some cardiac thickening," says Dr. Bonita Falkner, a professor of medicine and pediatrics at Thomas Jefferson University in Philadelphia.
In the face of those grim numbers, the medical and pharmacological communities are scrambling. Drug companies are rolling out new medications to join the arsenal of blood-pressure drugs already on the shelves. Physicians are routinely checking pressure in younger and younger patients. Public-health officials are launching new information campaigns, trying to raise public awareness in the hope of getting to the at-risk population before it's too late. Such large-scale mobilization may be the only way to get the problem back in check. "There's good evidence hypertension can be controlled," says Dr. Darwin Labarthe, acting chief of cardiovascular health at the Centers for Disease Control and Prevention (CDC), "but it will take an intense, sustained effort."
BREAKING DOWN
One reason hypertension can be such a stubborn problem is that it involves so many of the body's interlocking systems, and lying at the center of it all is the heart. The heart doesn't so much pour blood through the circulatory system as punch it through, forcing six quarts of heavy liquid beyond the torso and out to remote provinces like the feet, hands and head. Unfortunately, the riptides of the circulatory system are not always kind to the vessels that have to carry the load. Every time the heart contracts, blood not only rushes ahead through the vessels but also presses against the walls. That pulse is the systolic pressure, the first number in your blood-pressure reading. When the heart relaxes between beats, the pressure eases too but only to a point. That is the diastolic pressure, the second number. The force of both pressures is measured by how high a pulsing artery can push a column of mercury in a blood-pressure monitor. In general, 120 mm during a beat and 80 mm between beats are considered normal.
But there are a lot of things that can throw off the calibration of the whole fragile system, starting with the vessel walls. When we're young, our vessels are healthy and springy, easily stretching and contracting to accommodate blood pressure as it rises and falls. The arteries, which are a type of muscle, even pulse to help keep blood moving along. But the fibers that make up the scaffolding of the vessel walls can take only so much flexing. As we age, the rubbery tissue slowly gets replaced with stiffer collagen. The vessels don't expand as well anymore, but the blood keeps rushing through at the same rate, increasing the pressure. The higher the pressure climbs, the more punishment the walls take, and the more collagen is added. "The vessel wall becomes almost like concrete," says Dr. Michael Weber, a past president of the American Society of Hypertension.
The kidneys too play a big role. The urinary and renal systems govern not only the quantity of water that is kept or dumped by the body but also its composition. Drain or retain too much sugar, potassium or countless other essential components, and the chemistry of the whole body goes awry. One of the things the kidneys keep an especially close watch on is salt. The more sodium you hold, the more water your body retains, storing it first in the bloodstream and then off-loading it into tissues. When your system gets waterlogged, overfilled vessels feel the strain.
The kidneys work hard to keep that from happening. If salt content is too high, the body's water content will be elevated too. The system responds by slowing down the manufacture of renin, an enzyme that increases water retention. Dialing back the renin also dials back the production of angiotensin, a protein that constricts blood vessels. Should the salt level fall too far, the body reverses the procedure, cranking up renin to hold on to water and releasing angiotensin to tighten vessels. There are a lot of things that can throw that system off, including kidney disease and tumors on the thyroid gland. In most cases, however, it's simply too little exercise, too much food and too much salt.
"The great majority of people with high blood pressure have what is called essential hypertension," says Labarthe. "That is high blood pressure that is a reflection of lifestyle."
Whatever the causes of hypertension, doctors have been pretty clear about what its yard markers are. A reading of 120/80 or below is considered normal; 140/90 marks the onset of hypertension; 160/100 is Stage 2 hypertension; 220/120 is the onset of what is known as malignant hypertension, pressure so high that fluid is squeezed from vessels into the brain and blood leaks out of capillaries into the liquid that fills the eyeballs. "Malignant hypertension is a medical emergency," says cardiologist Richard Devereux of Cornell University Medical College.
THE DAMAGE DONE
The sinister thing about hypertension is that most of the creeping harm it does happens without the patient's knowing it. People with malignant hypertension may experience such symptoms as headaches or coldness in the hands and feet, but they also may not. People with less severe hypertension may experience nothing at all until calamity strikes. One of the commonest of those pressure-related disasters is heart attack. The higher pressure climbs, the harder the heart has to pump to push the blood. Like any other muscle called on to do more work, the heart responds by enlarging, chiefly in the left ventricle, which is its main pumping chamber. Increased muscle mass is fine in the biceps, but it's bad in the heart, which must be lean and flexible to work as it should. Worse, if a person with hypertension has high cholesterol, the deteriorating condition of vessel walls creates rough spots that serve as toeholds for circulating fats. As fat collects into plaques, they can break free, particularly if vessels are repeatedly being slammed by blood rushing out from the overworked heart. Breakaway plaque can lead quickly to a heart attack.
The brain can take a bad hit too in the form of stroke. About 75% of strokes are caused by a blood clot or loose plaque racing through the system and lodging in the vessels of the brain, where it cuts off the flow of oxygenated blood. Other strokes are essentially hemorrhages, ruptures in brain vessels that give way under elevated pressure.
Scientists studying Alzheimer's disease have also uncovered a possible link to uncontrolled blood pressure. When they scrutinized the brain vessels of people who had died of Alzheimer's, they found that those with a history of hypertension during middle age had tiny changes that did not appear in healthy individuals. "The question is, Where do the micro changes come from--longstanding hypertension or high cholesterol?" says Dr. Richard Mayeux, co-director of Columbia University's Alzheimer's research center, who is studying the connection. If either of them turns out to be involved, controlling both may be an unexpected way to reduce dementia risk.
With that surprising exception, the basic health issues associated with hypertension have not changed. What's new is how deep the pool of at-risk people has become and how serious the danger for them is. The National Heart, Lung and Blood Institute (NHLBI) estimates that of 65 million hypertensive Americans, nearly 20 million are not aware they have the condition. Worse, the 65 million figure is just an estimate of the vulnerable population, and that population is a constantly moving target. Every time the nation's obesity needle ticks upward, the number of hypertensive Americans does too.
What's more, the closer experts look at how doctors actually diagnose high blood pressure, the more they think they've been grading on a too generous curve. Traditionally, readings between 120/80 and 140/90 have been labeled borderline, less likely to require drugs or other intervention. Now the NHLBI believes that patients may begin approaching danger when their systolic reading--the first number--is as low as 115. Although pressure varies from moment to moment and day to day, a reading that hits the danger zone on two separate visits to the doctor may signal trouble.
"There is a doubling of cardiovascular risks that begins at this point," says Dr. George Bakris of Rush University Medical Center in Chicago. That means up to 45 million people who thought they were on safe ground may be at risk.
To try to make this point as emphatically as possible, the NHLBI labels the borderline pressure range "prehypertension," a mildly alarming term that was chosen for precisely that reason. "We convened focus groups; presented them terms such as high normal, borderline and abnormal vascular response; and asked them which would get across the idea that they had to take action," says Bakris. "Ninety-eight percent said prehypertension would do it."
CULTURE CLUB
If the nation's hypertension problem is going to be controlled, epidemiologists know that one place they're going to have to start is in the Latino and black communities. Mexican Americans have a hypertension incidence 5.5% higher than that of whites, and African Americans a whopping 43% higher. Epidemiologists have advanced any number of explanations for the hypertension problem in the black population. One of the most intriguing--if least provable--has been that the brutal conditions aboard slave ships crossing the Atlantic served as a sort of adaptive choke point, selecting for people with a tendency to retain salt and water. This allowed them to survive the murderous journey without succumbing to thirst but predisposed their descendants to hypertension. Dr. Lawrence Appel of the Johns Hopkins University School of Med-icine believes that modern-day African Americans do process sodium a bit differently from whites and may even have a less reactive renin-angiotensin system.
But while many researchers concede that genes may play such a role, they believe cultural variables are far more important. "African Americans generally have lower economic well-being and the ability to make lifestyle changes and purchase medicines," says the CDC's Labarthe. Indeed, a 10-country, 85,000-person study revealed that, worldwide, it is whites who are as much as twice as likely to suffer from hypertension, with countries like Poland and Finland--where diets are high in fat and low in fruits and vegetables--leading the way. In a socioeconomic environment in which African Americans are often forced to eat cheap, unhealthy food (the National Institutes of Health is worried particularly about cured meats, pickled foods, canned fish, salty snacks and sauces), it's no wonder their blood pressure is high.
Pregnant women are another high-risk group, whether they had hypertension going into the pregnancy or not. High pressure during pregnancy--160/110 or above--can lead to maternal seizures and even death. It can also cause premature births or stillbirths.
The newest and most surprising at-risk population, however, is the kids, a group in which hypertension, until recently, could not even be uniformly diagnosed. Optimum blood pressure changes with age and body size, and what's right for an adult is wrong for a preteen, to say nothing of a baby. A 2-year-old girl in the 50th percentile for height may have an average blood pressure of just 88/45. That same girl at age 10 should be up to 102/60, still far below the traditional adult benchmark of 120/80. The NHLBI now recommends making blood-pressure readings a part of all visits to the pediatrician. Any child who repeatedly scores in the 95th percentile or above for height, age and sex should be considered in danger.
FIXING WHAT'S BROKEN
What to do when any patient--child or adult--has hypertension varies from case to case, but some steps are obvious. Smoking, which is potentially lethal for everyone, is poison for the hypertensive. Tobacco accelerates heart rate and constricts blood vessels, just what you want to do if you're trying to make a hypertension problem worse but a lousy idea if you want to get well.
Controlling weight is also vital. The body tunes and retunes a lot of dials to keep its blood pressure balanced, and obesity twists those knobs in all the wrong ways. For one thing, increased body mass means higher blood volume, straining the circulatory system. Carrying extra weight also causes the heart to overwork--no favor to a left ventricle that may already be enlarged. Additionally, people who are overweight generally don't get that way eating fruits, vegetables and lean meats; their diet tends to be high in salt, fats and processed foods, just the things hypertension feasts on.